Reinforcing bar splice with threaded collars

ABSTRACT

A reinforcing bar splice secures together reinforcing bar ends by utilizing, at both ends, both tapered-thread coupling and coupling involving a filler, such as a grout or an epoxy. The splice may include a central tapered-thread central sleeve or coupler, and a pair of collars that are screwed onto externally-threaded ends of the central sleeve. The central sleeve has a channel therethrough with tapered internal threads at both ends, and a center internal relief. The internal relief is an increased radius center portion that ensures full thread contact between the tapered internal threads and external threaded sections of the rebar ends. The sleeve has externally-threaded ends that are engaged by internally-threaded ends of a pair of collars. Distal to their internally-threaded ends, the collars have filler-material-receiving channels. The channels include plural sloped surfaces for aiding in securing filler material between the collars and the rebar ends.

This application claims priority under 35 USC 119 to U.S. ProvisionalApplication No. 60/758,687, filed Jan. 13, 2006.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

This invention relates generally to reinforcing bar splices.

2. Description of the Related Art

High tensile strength splices for reinforcing bar used in concreteconstruction have been widely employed. One type using a sleeve withinternal deformations employs as a locking element filler metal formedfrom an exothermic reaction, such molten metal entering the sleevethrough a tap hole. When the metal solidifies it forms a lock betweenthe deformation on the interior of the sleeve, and the typicaldeformations found on the exterior of the reinforcing bar. These typesof splices are sold by ERICO Inc. of Solon, Ohio, under the trademarkCADWELD®. Examples of such splices may be seen in prior U.S. Pat. Nos.3,234,603 and 3,255,498, to Leuthy et al.

Another type of reinforcing bar splice that is widely employed is athreaded splice connection. A sleeve with internal threads is threadedinto a bar with external threads. One such system which is widelyemployed and frequently specified is a taper thread system such as thatmade and sold by ERICO Inc. of Solon, Ohio under the trademark LENTON®.

Another type of splice is a grout splice system, such as that shown inYee, U.S. Pat. Nos. 3,540,763 and 4,672,212. These patents use a sleevewith internal deformations and a volume stable grout to form a lockingelement within the sleeve locking on the internal deformations of thebar, much like the metal of the earlier Leuthy patents.

All of these methods have their advantages and disadvantages, and noneis ideal for all situations. Therefore there is room for improvement inthe area of reinforcing bar splices.

SUMMARY OF THE INVENTION

According to an aspect of the invention, a reinforcing bar spliceincludes: an internally threaded sleeve, and a pair of internallythreaded collars that engage externally threaded ends of the sleeve. Thecollars have openings that are configured for receiving reinforcing barends, and securing the bar ends therewithin using an epoxy or grout.

According to another aspect of the invention, a reinforcing bar spliceincludes an internally threaded section for threadedly engaging taperedthread ends of reinforcing bars, and wider sections at distal ends ofthe splice, for engaging the reinforcing bars with a grout or epoxy. Thewider sections may have ramped or sloped surfaces for improving theholding of the grout or epoxy.

According to yet another aspect of the invention, an internally taperedthreaded reinforcing bar splice has a central relief therein. Thecentral relief relieves thread stress concentrations, which may helpretard fatigue crack initiation.

According to still another aspect of the invention, a reinforcing barsplice engages each of a pair of reinforcing bar ends with both taperedthreads and an epoxy or grout.

According to a further aspect of the invention, a tapered threadreinforcing bar splice achieves improved fatigue performance bytransferring some of the load from a tapered thread portion of thesplice to an epoxy- or grout-filled portion of the splice.

According to another aspect of the invention, a reinforcing bar spliceincludes: a sleeve having sleeve internal tapered threads at oppositesleeve ends; and a pair of collars mechanically coupled to the ends, andextending axially beyond the sleeve ends.

According to yet another aspect of the invention, a method of couplingreinforcing bar ends, includes the steps of: securing in externaltapered thread portions of the reinforcing bar ends in opposite internaltapered thread ends of a sleeve; and placing filler material between thereinforcing bar ends and collars that are mechanically coupled to thesleeve. The filler material may include a grout and/or an epoxy.

To the accomplishment of the foregoing and related ends, the inventioncomprises the features hereinafter fully described and particularlypointed out in the claims. The following description and the annexeddrawings set forth in detail certain illustrative embodiments of theinvention. These embodiments are indicative, however, of but a few ofthe various ways in which the principles of the invention may beemployed. Other objects, advantages and novel features of the inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the annexed drawings, which are not necessarily to scale:

FIG. 1 is an oblique view of a reinforcing bar splice of the presentinvention, coupling together reinforcing bar ends;

FIG. 2 is an exploded view of the splice of the present invention;

FIG. 3 is an exploded, sectional side view of the splice of FIG. 1; and

FIG. 4 is a sectional side view of the splice of FIG. 1.

DETAILED DESCRIPTION

A reinforcing bar splice secures together reinforcing bar ends byutilizing, at both ends, both tapered-thread coupling and couplinginvolving a filler, such as a grout or an epoxy. The splice may includea central tapered-thread central sleeve or coupler, and a pair ofcollars that are screwed onto externally-threaded ends of the centralsleeve. The central sleeve has a channel therethrough with taperedinternal threads at both ends, and a center internal relief. Theinternal relief is an increased radius center portion that ensures fullthread contact between the tapered internal threads and externalthreaded sections of the rebar ends. The sleeve has externally-threadedends that are engaged by internally-threaded ends of a pair of collars.Distal to their internally-threaded ends, the collars havefiller-material-receiving channels. The channels include plural slopedsurfaces for aiding in securing filler material between the collars andthe rebar ends. The sloped surfaces also transfer some of the load fromthe rebar ends to the collars, thus reducing the amount of load on thetapered coupling between the bar ends and the central sleeve. The fillermaterial may be an epoxy or grout, or may alternatively be anothersuitable material, such as a reactive metal-producing material.

FIGS. 1-4 show a reinforcing bar splice or coupling 10 joining togethera pair of reinforcing bar ends 12 and 14. The splice 10 includes acentral sleeve 16, and a pair of collars 18 and 20 that are physicallycoupled to ends of the central sleeve 16. In short, the reinforcing barends 12 and 14 are coupled to the sleeve 16 by an engagement of taperedthreads, and are coupled to the collars 18 and 20 by a suitable fillermaterial, such as epoxy or grout.

The sleeve 16 includes a central through-hole 24. The ends 26 and 28 ofthe sleeve 16 are internally threaded along the hole 24 at taperedthread portions 30 and 31 of the hole 24, with respective taperedthreads 32 and 34. The tapered threads 32 and 34 are configured toengage corresponding externally-threaded tapered portions 36 and 38 ofthe rebar ends 12 and 14. The rebar ends 12 and 14 are coupled to thecentral sleeve 16 by rotating the ends 12 and 14, and/or the sleeve 16,to threadedly engage the rebar end threaded portions 36 and 38 with thetapered threads 32 and 34 of the sleeve. In this manner the sleeve 16becomes a tensile and compressive extension of the reinforcing bar ends12 and 14. Further details regarding threaded rebar coupling may befound in U.S. Pat. No. 5,366,672, the description and drawings of whichare herein incorporated by reference.

The sleeve 16 has a center internal relief 40 in a center portion of thehole 24. The internal relief 40 is an increased radius center portionthat ensures full thread contact between the tapered internal threads 32and 34 and the external threaded sections or portions 36 and 38 of therebar ends 12 and 14. The internal relief 40 ensures that the rebar ends12 and 14 can be inserted in the sleeve through-hole 24 past the lastengaged thread of the internally-threaded portions 32 and 34. Theinternal relief 40 also relieves thread stress concentrations, and thusmay help eliminate or retard fatigue crack initiation.

The sleeve 16 has external threads 42 and 44 at the sleeve ends 26 and28. The external threads 42 and 44 engage respective first (proximal)ends 48 and 50 of the collars 18 and 20. The collar first ends 48 and 50have internal threads 52 and 54 configured to engage the sleeve externalthreads 42 and 44, to couple the collars 18 and 20 to the sleeve ends 26and 28. The collars 18 and 20 are coupled to the sleeve ends 26 and 28by suitable aligning and rotating the collars 18 and 20 and/or thesleeve 16 to threadedly engage them.

The collars 18 and 20 have respective through-holes 52 and 54 forallowing the rebar ends 12 and 14 to pass therethrough for threadedcoupling to the central sleeve 16. As described in the previousparagraph, at the first collar ends 48 and 50 the through-holes 52 and54 are internally threaded to engage the sleeve ends 26 and 28. Atsecond (distal) collar ends 58 and 60 the through-holes 52 and 54 haverespective filler-material-receiving channels 62 and 64. The channels 62and 64 have a diameter that is greater than that of the rebar ends 12and 14. The diameter of the channels 62 and 64 is also greater than amaximum diameter of the sleeve through-hole 24 at the internal threads32 and 34 (at the mouths of the through-hole 24). The channels 62 and 64are sized to allow entry of filler material 66 after the rebar ends 12and 14 have been inserted through the collars 18 and 20, and threadedlyengaged with the central sleeve 16. Thus spaces 68 and 70 within thecollars 18 and 20, around the rebar ends 12 and 14, may be filled withthe filler material 66, to aid in securing the rebar ends 12 and 14.

The channels 62 and 64 each include plural sloped surfaces for aiding insecuring filler material between the collars and the rebar ends. In theillustrated embodiment each of the channels 62 and 64 has four slopedsurfaces, although it will be appreciated that a greater or lessernumber of sloped surfaces may be employed. The channel 62 has slopedsurfaces 71, 72, 73, and 74, and the channel 64 has sloped surfaces 75,76, 77, and 78. The sloped surfaces 71-78 are angled so that they aredirected radially inward, such that they are closer to the rebar ends 12and 14 where they are closer to the distal collar ends 58 and 60, awayfrom the sleeve 16. The sloped surfaces 71-78 transfer some of the loadfrom the rebar ends 12 and 14 to the collars 18 and 20, thus reducingthe amount of load on the tapered thread coupling between the bar ends12 and 14, and the central sleeve 16. Because of the sloped surfaces71-78, tensile stresses on the rebar ends 12 and 14, are in partconverted into compression stresses in the filler material 66. Thesecompression stresses in the filler material 66 are converted, via thesloped surfaces 71-78, into hoop stresses in the collars 18 and 20.Since filler materials such as grout or epoxy are stronger incompression than in tension, it will be appreciated that it isadvantageous to transform tension stresses in the rebar end 12 and 14,into compression stresses in the filler material 66. Further, thecollars 18 and 20, being made of metal, resist hoop stresses very well,and therefore it is advantageous to dissipate compression stresses inthe filler material 66 as hoop stresses in the collars 18 and 20.

The sleeve 16 and the collars 18 and 20 may be made of a suitablematerial, such as steel. The filler material for the collars 18 and 20may be an epoxy or grout, or may alternatively be another suitablematerial, such as a reactive metal-producing material, such as used inERICO systems sold under the trademark CADWELD®.

In assembly, the collars 18 and 20 are first threadedly engaged on theexternal threads 42 and 44 of the sleeve ends 26 and 28. Then the rebarends 12 and 14 are threadedly engaged with the internal tapered threads32 and 34. (The two proceeding steps may be reversed in order, ifdesired.) Finally the spaces 68 and 70 are filled with the fillermaterial 66. A grout or epoxy filler material is allowed to cure, tocomplete the splice 10.

The splice 10 advantageously disperses or spreads stress out over alarger area of the rebar ends 12 and 14. Since some of the stress on therebar ends 12 and 14 is transferred to the collars 18 and 20, ratherthan the central sleeve 16, the splice 10 is better able to withstandstress, and may have better fatigue performance.

The splice 10 has better performance than conventional tapered threadsplices with regard to two fatigue failure modes. One mode whereconventional tapered thread splices fail is due to failure of the rebarat the middle of the tapered thread sleeve. The presence of the internalrelief 40 at the middle of the sleeve 16 helps prevent this type offailure.

Another type of failure in conventional tapered thread splices isfailure of the rebar at the mouth of the tapered thread sleeve, wherethe rebar ends exit the sleeve. The presence of the filler material 66at this location in the splice 10 helps reduce stresses, aiding inavoiding this sort of failure as well.

It will be appreciated that the splice 10 shown in the figures anddescribed above is but one embodiment of the invention. Many variationsare possible, including different ways of physically coupling a sleeveand collars, and different ways of configuring the sleeve and/or thecollars. Some of the features described herein may be omitted, ifdesired, or may be combined with other features.

Although the invention has been shown and described with respect to acertain preferred embodiment or embodiments, it is obvious thatequivalent alterations and modifications will occur to others skilled inthe art upon the reading and understanding of this specification and theannexed drawings. In particular regard to the various functionsperformed by the above described elements (components, assemblies,devices, compositions, etc.), the terms (including a reference to a“means”) used to describe such elements are intended to correspond,unless otherwise indicated, to any element which performs the specifiedfunction of the described element (i.e., that is functionallyequivalent), even though not structurally equivalent to the disclosedstructure which performs the function in the herein illustratedexemplary embodiment or embodiments of the invention. In addition, whilea particular feature of the invention may have been described above withrespect to only one or more of several illustrated embodiments, suchfeature may be combined with one or more other features of the otherembodiments, as may be desired and advantageous for any given orparticular application.

1. A reinforcing bar splice comprising: a sleeve having sleeve internaltapered threads at opposite sleeve ends; and a pair of collarsmechanically coupled to the ends, and extending axially beyond thesleeve ends.
 2. The splice of claim 1, wherein the collars have collarinternal threads at distal collar ends that threadedly engage sleeveexternal threads at the sleeve ends.
 3. The splice of claim 2, whereinthe collars have respective channels at proximal ends that havediameters greater than maximum diameters of tapered-thread portions ofthe sleeve.
 4. The splice of claim 3, further comprising filler materialin the channels.
 5. The splice of claim 4, wherein the filler materialincludes an epoxy.
 6. The splice of claim 4, wherein the filler materialincludes a grout.
 7. The splice of claim 3, wherein each of the channelshas plural sloped inner surfaces, wherein the sloped inner surfaces havea smaller diameter closer to the distal end of the collar.
 8. The spliceof claim 1, wherein the sleeve has a through-hole; and wherein thesleeve internal tapered threads are at tapered-thread portions atopposite ends of the through-hole.
 9. The splice of claim 1, wherein thesleeve has an internal relief at a central portion of the through-hole.10. The splice of claim 1, in combination with a pair of rebar ends;wherein the rebar ends have external tapered thread portions threadedlyengaged with the internal tapered threads of the sleeve.
 11. Thecombination of claim 10, further comprising filler material in spacesbetween the collars and respective of the rebar ends.
 12. Thecombination of claim 11, wherein the filler material includes one ormore of an epoxy and a grout.
 13. The combination of claim 12, whereinthe collars have collar internal threads at distal collar ends thatthreadedly engage sleeve external threads at the sleeve ends.
 14. Thecombination of claim 13, wherein each of the channels has plural slopedinner surfaces, wherein the sloped inner surfaces have a smallerdiameter closer to the distal end of the collar.
 15. The combination ofclaim 14, wherein tensile stresses on the rebar ends is converted atleast in part to compressive stresses in the filler material, which inturn is converted at least in part to hoop stresses in the collars. 16.The splice of claim 15, wherein the sleeve has a through-hole; andwherein the sleeve internal tapered threads are at tapered-threadportions at opposite ends of the through-hole.
 17. The splice of claim16, wherein the sleeve has an internal relief at a central portion ofthe through-hole.
 18. A method of coupling reinforcing bar ends, themethod comprising: securing external tapered thread portions of thereinforcing bar ends in opposite internal tapered thread ends of asleeve; and placing filler material between the reinforcing bar ends andcollars that are mechanically coupled to the sleeve.
 19. The method ofclaim 18, wherein the filler material includes at least one of an epoxyand a grout.